1. Field of Use
This invention relates generally to a chiropractic thruster for use in chiropractic treatment to apply impact forces or thrusts to a human body.
2. Description of the Prior Art
Percussor or impact devices of the aforesaid character are known and the following patents and article show the state of the art.
U.S. Pat. No. 1,657,765 issued in 1928 to Pasque discloses an electromechanical massage, vibratory or percussor apparatus which effects repeated reciprocatory motion of an adjustally positionable impact head in response to rotation of a motor-driven cam and the stroke length of the impact head can be adjusted.
U.S. Pat. No. 2,078,159 issued in 1937 to Redding discloses a vertebral adjuster in which a reciprocally movable spring-biased head delivers a single impact whenever a trigger-operated pin releases a piston which is driven in the impact direction by compressed air in a reservoir. The piston is returned to its start position by gravity when the device is tilted upwardly manually while the trigger is still depressed.
U.S. Pat. No. 2,204,259 issued in 1940 to Schuster et al discloses a spinal adjustment device wherein a cam driven by an electric motor imparts one blow to an adjustably positionable rubber-tipped reciprocable rod, spring-loaded at each end, each time a trigger-operated lever mechanically raises the cam into rod-striking position.
U.S. Pat. No. 3,955,563 issued in 1976 to Maione discloses a pneumatic percussor wherein a spring-return plunger reciprocally vibrates in response to compressed air pulses provided through an electronically pulsed air supply control valve.
U.S. Pat. No. 4,016,873 issued in 1977 to Anderson discloses a pneumatic impacter wherein a rubber-tipped reciprocally movable spring-biased plunger delivers a single stroke in response to each operation of a trigger-operated valve which admits compressed air from a reservoir to a piston on the rear end of the plunger.
U.S. Pat. No. 4,461,286 issued in 1964 to Sweat discloses a mechanical chiropractic instrument wherein a reciprocally movable thrust pin is propelled outwardly by a spring to impart a single blow each time a trigger is actuated to release a spring-loaded adjustably positionable percussion device which strikes the trust pin and such instrument needs to be manually reset to recharge the spring after each blow.
An article in the November/December 1984 edition of The Digest of Chiropractic Economics entitled "The Force Of The Activator Adjusting Instrument" by Mark L. Duell, B.S., D.C., discloses an activator adjusting instrument and test data relative thereto.